package com.cong.leetcode._23;


import java.util.HashSet;
import java.util.Set;

class Solution {
    public static class ListNode {
        int val;
        ListNode next;

        ListNode() {}

        ListNode(int val) {
            this.val = val;
        }

        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public ListNode mergeKLists(ListNode[] lists) {
        Set<Number> s = new HashSet<>();
        return null;
    }
}